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Finding the Fourth Proportional to 939.15, 1,407.51 and 390.96

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Solution

The fourth proportional to 939.15, 1,407.51 and 390.96 is: 585.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.15 : 1,407.51 = 390.96 : x
  2. Step 2: Convert to fraction form
    939.15/1,407.51 = 390.96/x
  3. Step 3: Cross multiply
    939.15x = 1,407.51 × 390.96
  4. Step 4: Simplify right side
    939.15x = 550,280.11
  5. Step 5: Solve for x
    x = 550,280.11/939.15
  6. Step 6: Final answer
    x = 585.93

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.